Change multiple product names

I have over 20 categories in an oscommerce store. Each category has over 1000 products. The products in each category have the same name as the next category. I can change the category names no problem but I need to change the names of all the products in each categroy so they are not the same, but it would take a long time to change over 20000 product names individually. Im looking to pay $50 max for a solution Im looking for a service provider who can provide an already made script or a solution to allow me to change the names quickly. Im thinkinig something like the find and replace all feature from Dreamweaver? So I could search for aaaa and change it to bbbbb in all the products that had aaaa in their name in that categroy.